Landscapes Forest and Global Change - ESA - Escola Superior ...

M.L.Leite & J.S.V. Filho 2010. Identification of climatic trends for some localities in the Southern Region of Campos Gerais
384
cities of Lapa and Fernandes Pinheiro, the latter being significant at 0.01%, while for the city of
Ponta Grossa, the maximum temperature had a significant negative trend of 0.01%. For
minimum temperature, all the cities had significant positive trends, showing a rise in the
minimum temperature in the region. These results of a temperature rise in the southern region of
Campos Gerais, in the State of Parana, is reinforced by analyzing the average temperature in the
three localities, which showed positive trends. Finally, for the city of Ponta Grossa, in despite of
having observed an average temperature rise, this was not significant for the studied period.
4. Discussion
According to Silva (2004) the rainfall in southern Brazil are distributed regularly throughout the
year, compared to other regions of the country, but in recent years the phenomenon El Nino has
served continuously in this region. This climatic phenomenon, when actuates, significantly
alters the levels of rainfall, which are increased during the year. Whereas this phenomenon has
been acting steadily in the region, the increase in the totals of annual rainfall and the positive
trend observed for the city of Ponta Grossa may be correlated with the performance of such a
frequent phenomenon in the region. Back (2001) also found elevated totals of annual rainfall for
the city of Urussanga, State of Santa Catarina, identifying a significant positive trend. The
decrease of the maximum temperature in Ponta Grossa, along with higher minimum temperature,
can be partially explained as a consequence of increased cloudiness in the region. Due to this
rise in the levels of cloudiness during the day, a smaller amount of sunlight can reach the earth's
surface, occurring a decrease in maximum temperature. During the night, with lots of clouds,
there is greater retention of radiation, complicating its loss to space, thereby increasing the
minimum temperature at location (Silva & Guetter, 2003). In a previous study, Silveira & Gam
(2006), analyzing changes in minimum temperatures in southern Brazil, found that the
minimum temperature in the state of Rio Grande do Sul also showed a positive trend over the
study period under review. The same increases were verified by Obregon & Marengo (2007),
which developed a major study on climate throughout the Brazilian territory, in order to
determine possible changes in climate variables. In this study the annual minimum temperatures
in the city of Curitiba, Brazil, showed a significant positive trend at 0.05%, reinforcing the
findings of elevated temperatures in the State of Parana. One reason for this increase in
temperatures can also be correlated to the increase in the totals of areas destinated to
urbanization in the last years (Sansigolo et al., 1992). In some regions, deforestation and
changes in land use, as a result of human activities have increased rapidly in recent decades, and
there are evidences that these actions can modify the thermodynamic characteristics of the
lower atmosphere. These changes are the result of complex interactions between climate,
hydrology, vegetation and management of water resources and land.
Acknowlegments
The authors thank to the Instituto Agronômico do Paraná (IAPAR) for the authorization to
access the rainfall data, and to the SETI – Fundação Araucaria, by the research support.
References
Back, J.A., 2001. Aplicação de análise estatística para a identificação de tendências climáticas.
Pesq. Agropec. Bras., 36, n. 5: 717-726.
Groisman, P., Knight, R., Easterling, D., Karl, T., Hegerl, G., Razuvaev, V., 2005. Trends in
tense precipitation in the climate record. Journal of Climate, 18: 1326-1350.
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.